The Type A turret proved an efficient design, its low profile
causing a minimum of drag to the aircraft. The Hele-Shaw-Beacham hydraulic variable gear system provided a very smooth
operating movement in both traverse and elevation. The gunner's view was not ideal, being impeded by the guns and feed
mechanism, but he had a reasonable view to his front and directly to each beam. The four Browning guns were mounted in
pairs on either side of the turret, while to the gunner's front was the control table with the following operating
This control had two positions. When pulled to the rear
'Free' position the rotation drive was disconnected mechanically and the connections to the hydraulic elevation rams
short-circuited through a bypass valve. When pushed forward to the 'Engaged' position, the turret was operational.
The gun master switch was a three-position switch marked
PILOT, OFF, GUNNER. The PILOT position was never used and was disconnected, being in effect another OFF position; when
the GUNNER position was selected the gun firing circuit was alive.
The control column - 'joystick' - was on the right of the
control table projecting through a diamond-shaped aperture. Movement of the column controlled the output from the
hydraulic generator, and thus the speed and direction of elevation and rotation. A grip lever on the column energised
the elecrtic-motor armature when grasped, and a gun-firing button on the top of the column was operated by the gunner's
On the right of the control panel over the gun switch was the
motor main switch, which when closed energised the field of the motor and was indicated by a red warning lamp. The
turret could then be operated from the control column.
In the centre of the table was a red button. When this was
pressed it connected a resistance in series with the motor field winding, which doubled the speed of the motor and
enabled the gunner to change quickly from one target to another. The button was used only for short periods as it
imposed an overload on the motor and hydraulic system.
If the power system failed the turret could be operated by a
hand rotation mechanism. A small handle was stowed under the right armrest. This was fitted to a gear shaft and, with
the disengaging lever to FREE, the turret could be rotated. It was also just possible to elevate the guns by pressing
the back end of the breeches. To see how this turret was operated, take a look in this interesting movie. The
life of an air gunner was pretty tricky !
The four Browning Mk.II guns were mounted on their sides with
the cocking levers upper-most: they were cocked by the usual looped lanyard. Four 600-round ammunition boxes were fixed
in front of the gunner's legs, the ammunition belts being lifted from the boxes by the gun feed mechanism over 90 degree
chutes. Spent cartridges and links were collected in collapsible bags below the guns. The guns were fired by electrical
solenoid sear-release units; the gun button operated a relay which energised the releases. Sighting was by a Mk.IIIA
reflector sight mounted on an arm which moved in unison with the guns, the sight switch being on the left of the control
table. An adjustable floodlight controlled from a switch under the sight switch enabled the gunner to clear stoppages on